Windows and MacOS devices are not the best way to present a BimX.
The best way to present a BimX is on a iPad Pro 13" in your client hand.
You are able to use a Apple TV to get a mirroring of your iPad screen without cable or you can use a câble to link your iPad to a 4K TV.
With your project in their hands, your client will no longer need 4K to be seduced.
Thank you for reporting the issue and I am sorry about the experience!
Could you be a bit more specific on the issue that you are having:
- Which BIMx application and platform are you using?
- How do you show/transmit the BIMx model to 4K screen
- Can you make a screenshot on how awful does it look on the screen?